The main method of cleaning main line stoppages in the sewer system of a house is to send a "snake" comprising a cable with a cleaning head on the end from the vent terminus at roof level. The plumber sets his source machine up using conventional cable and 7/8" heads and runs the cable through his machine, down the stack to the obstruction which may be grease, hair, etc. Problems arise, however, when the stack size at the roof has been reduced in pipe size to a size too small for the conventional 7/8" cleaning heads. This is a common construction practice today, and in older homes in the southern states especially, where kitchen sink stacks were always reduced to 11/2" diameter at roof level but are 2" below floor level. The plumber must use a cleaning head to scour the inside of the pipe to effectively clean the grease, etc., but the size of the stack limits the size of the cleaning head, thus limiting the quality of the plumber's work, possibly resulting in frequent return visits.
Presently, the plumber has a few costly alternatives for entering this stack. He must use a smaller cleaning/cutting head that is adaptable to a conventional cable. The other alternative is to resort to the next size smaller cable, 5/8, for the smaller cable machine. There are two ways to do this: one is to buy the whole new, smaller machine, cable and heads just for this purpose, at a considerable expense. The other is to buy the adapter, which is a sleeve to insert into the larger machine, allowing it to accept the smaller cable and heads. This is also very costly, as one must buy the adapter, the 5/8" cable, and the heads. This is also inefficient, as this machine is made for 7/8" cable pushing smaller size cable, which is subject to kinking under stresses encountered in the main line stoppages, especially as the length of cable increases. The plumber must also carry around an extra machine and cable (at least 75 feet) in his truck, which normally already has enough equipment and tools inside.